A 42-year-old female with gradual-onset dyspnea on exertion and a systolic murmur is presented, in whom electrocardiogram showed left axis deviation with an Rsr' pattern in lead V1. Chest X-ray had a pulmonary vascular shunt and echocardiography marked a large ostium primum atrial septal defect together with a cleft in the mitral valve, leading to a diagnosis of the partial atrioventricular septal defect. Furthermore, magnetic resonance imaging depicted an incidental cyst on the roof of the left atrium. The operation was performed, and the cyst was excised. It measured 15 mm in diameter, had a fibrotic wall and contained homogeneous gelatinous material. Histopathology showed a small simple cyst with a fibrotic wall, lined by cuboidal to respiratory-type columnar cells. No evidence of malignancy was noted. The patient had an uneventful postoperative course and was discharged in good clinical condition.

Here, we discuss a rare case report, the aim of which is to present an incidentally found congenital anomaly, not a neoplasm. Echocardiography, cardiac magnetic resonance imaging (MRI), and histopathology serve as clues to a better approach.

Case Report

We present a 42-year-old female with a chief complained of dyspnea on exertion of gradual onset. Her physical examination revealed a systolic murmur over the pulmonary valve area but was otherwise unremarkable. The electrocardiogram showed left axis deviation with an Rsr' pattern in lead V1. Her chest X-ray portrayed the evidence of a pulmonary vascular shunt and echocardiography further revealed a large ostium primum atrial septal defect together with a cleft in the mitral valve. These echocardiographic findings lead to a diagnosis of partial atrioventricular septal defect (AVSD). Given the small size of the left ventricle (LV) and to better evaluate the size and the volume of LV regarding operability, a cardiac MRI was requested. Later, MRI depicted the LV size at the lower limit of normal and interestingly enough, an incidental cyst was found on the roof of the left atrium [Figure 1]. The operation was performed on the patient, which consisted of AVSD repair and cyst excision. The cyst measured 15 mm in diameter, had a fibrotic wall, and contained homogeneous gelatinous material. Grossly, the specimen consisted of soft and creamy-gray fragments, 1.5 cm in diameter. The histopathological examination showed a small, simple cystic structure with a fibrotic wall, lined by cuboidal to columnar cells [Figure 2]. The latter was reminiscent of the ciliated respiratory-type epithelium. Neither evidence of malignancy was noted nor was any neuroectodermal element to suggest a probable diagnosis of a mediastinal teratoma. The patient had an uneventful postoperative course and was discharged in good clinical condition.

Figure 1: Arrow shows the position of a 15 mm cyst on the roof of the left atrium

Foregut cysts appear as a result of anomalous embryonic development. A sac-like cyst may be pinched off during this developmental period, being carried into the mediastinum as a result of the downward growth of the lungs. This cyst contains endodermal and mesodermal elements that were to become a part of the respiratory tract, esophagus, stomach, or intestine. Therefore, the foregut cyst, which is a general term encompasses bronchogenic, esophageal, gastric, or enteric cysts. Bronchial cysts are noted along the tracheobronchial tree, most commonly posterior to the carina or rarely, above the diaphragm. These cysts have clear or gelatinous fluid and are predominantly unilocular with a thin wall. Their average size is about 3–4 cm. Microscopically, it is usual to see ciliated columnar epithelium and foci of squamous metaplasia.[1] Intracardiac foregut cysts can be diagnosed with transthoracic echocardiography as a space-occupying lesion with compressive effects; hence, the reduction in cardiac function or blood flow obstruction. Diagnosis is by histopathology, in which, we see endodermal and mesodermal elements. Teratomas are the main differential diagnosis of foregut cysts, in which, we see ectodermal elements too.[2] Intracardiac bronchogenic cysts are extremely rare, with only three cases reported previously. A similar lesion was found in a 70-year-old male who had a bronchogenic cyst in interatrial septum and a concomitant persistent left superior vena cava.[3] We presented this case because of its rarity and association with congenital heart disease, partial AVSD. Whereas, these cysts occur usually in the mediastinum, the heart is an atypical location for such lesions, and in our case report, we have described a rare lesion in a yet rarer location.[4]

Declaration of patient consent

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